Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various layers using lithography to form circuit components and elements thereon.
Semiconductor devices are typically packaged as single die or in multi-chip modules. Many different types of packaging are used, and packaging techniques have changed throughout the years as semiconductor devices are scaled down in size and according to the end application that they are used in. Factors such as performance, size, weight, and operating conductions influence the type of packaging selected. In-line packages, small outline packages, quad surface mount, and array packages are examples of some major package families.
Array packages provide the ability to increase the lead count, reduce the footprint of the package, and reduce the length of interconnections between the die and the board. Array packages include pin grid array (PGA) packages, chip scale (CS) packages, and ball grid array (BGA) packages. BGA packages have an array of solder balls arranged across the bottom of the package. A die is mounted on top of a base and the die is electrically connected to the base using wire bonds or solder bumps. BGA packages are available that have several hundred, e.g., 300 or greater pin counts. Land grid array (LGA) packages are similar to BGA packages, without the solder balls.
However, the coefficient of thermal expansion is different for the various material layers in BGA, LGA, and other wafer level packages, which can lead to bowing and warping of the packages. The bowing and warping of the packages can cause cracking in the solder bonds, disconnects, and device failures.
Thus, what are needed in the art are improved packaging systems and methods for integrated circuits.